1. Field of the Invention
The present invention relates to an apparatus for measuring the geometry of a person""s plantar contour and a method of forming a custom insole corresponding to the measured plantar contour. More particularly, the present invention relates to an impression block for taking a partial measurement of the plantar contour that can be extrapolated to produce a custom insole.
2. Description of the Related Art
A number of methods currently exist to measure the geometry of the plantar contour of a foot. The accurate measurement of the plantar contour is used in the manufacture of custom insoles. The prior art methods include plaster casting, optical scanning, contact sensor measurement, as well as impression measurement. These methods prefer the foot to be in a neutral position. However, some shoes, such as high heels or other shoes with a slope, distort the plantar contour and instep due to the shifting of the user""s body weight. Accordingly, the insoles made using these prior art methods do not account for such distortions. Moreover, these prior art methods are not well suited for home use.
The optical scanning methods and contact sensor measurement methods utilize expensive equipment. These methods provide an accurate and complete measurement of the foot. But, the size, expense and complexity of the equipment necessary for these methods makes them not suitable for use in all locations. Moreover, these methods do not permit accurate measurement of the geometry of the foot in the position it will be in when inside of a shoe.
Plaster casting methods require the measurement to be performed by a person other then the one being measured. This method provides an accurate and complete measurement of the foot but can be very messy and time consuming. Thus, plaster casting methods are not suitable for use in a person""s home or by one""s self. Moreover, these methods do not permit accurate measurement of the geometry of the foot in the position it will be in when inside of a shoe.
Impression measurement methods and apparatus utilize an easily deformable block. A person steps onto the block, thus crushing the block in the locations of higher pressure. In this manner, the block deforms in the approximate shape of the persons"" plantar contour. While this prior art method may be suitable for home use, it produces a sub-optimal characterization of the foot for a number of reasons. First, the block is uniform in thickness from heel to toe. This causes the toes to be forced upward as the foot is pressed into the block because the toes of the foot have substantially less pressure on them than the region of the foot from the heel to the metatarsal heads. Forcing the toes upward can cause a number of problems including, hyperextension of the plantar fascia, lowering of the correct arch height, and improper measurement of the forefoot and heel. Second, under full body weight, the foot expands allowing for a larger than normal foot impression. Additionally, the prior art does not provide for measurement of the instep. Moreover, the current materials and methods do not permit accurate measurement of the geometry of the foot in the position it will be in when inside of a shoe.
In the manufacture of custom insoles, the use of the plaster casting and impression methods also require the use of a scanning system. The scanning system may act directly on the negative impression within the block or plaster. Scanning systems that act directly on negative impressions are known in the art. These laser-scanning systems consist of a laser with a line generating optic. The laser projects a line at a known incident angle onto the negative impression. A camera is used to read the position of the laser line on the negative impression. Alternatively, the scanning system may act upon a positive model using a casting medium such as plaster, wax or equivalent made form a negative impression contained in the foam block. One such scanning system, provided by U.S. Pat. No. 4,876,758, specially constructed array of pin-like sensors. In either circumstance, the scanning system is used to digitize the measured contour. The digitized contour is provided to a computer controlled milling machine. The milling machine uses the digitized information to manufacture a custom insole matching the digitized contour. Accordingly, the apparatus and methods of the present invention provide for cheaper, improved and easier means to provide custom manufactured insoles to a customer.
Previously, the prior art impression block is required to measure the entire plantar contour in order for the scanning system to create a digitize contour sufficient to manufacture the custom insole. More specifically, the prior art impression block requires a thickness equal to or greater than the thickness of the blank used to manufacture the custom insole. However, impression blocks of such thickness have many drawbacks, such as large shelf space requirements, increased packaging costs, and increased shipping costs. In the instance where the prior art impression block is directed for use at home by the user and then to be shipped to a location for manufacture of the insole, such thick prior art devices are simply not practical.
Accordingly, the present invention provides foot measurement apparatus and methods, which overcome the limitations set forth above.
The present invention provides an apparatus for measuring a plantar contour of a foot of a user. The apparatus comprises a carrier and an impression block in the carrier. The impression block has a guide formed therein to aid the user in aligning the foot with respect to the impression block.
The present invention also provides an apparatus for measuring a plantar contour of a foot of a user where the plantar contour has a height. The apparatus comprises an impression block having a thickness sufficient to form an impression of at least a portion of the height of the plantar contour.
Additionally, the present invention provides a method for forming a complete digitized model of the height of a plantar contour of a foot of a user, wherein the plantar contour has a height. The method comprises the steps of: (1) placing the foot of the user into an impression block having a thickness, wherein the thickness is sufficient to form an impression of at least a portion of the height of the plantar contour; (2) forming a digitized model of the impression; (3) extrapolating data from the digitized model of the impression to form the complete digitized model of the full height of the plantar contour; and (4) forming a digitized model of the portion of the plantar contour; and (5) fabricating an insole from the portion of the digitized contour.
An additional embodiment according to the present invention comprising an apparatus for measuring a plantar contour of a foot of a user having at least a portion of a shoe and an impression block disposed within the shoe, wherein the impression block has a guide formed therein to aid the user in aligning the foot with respect to the impression block. Preferably, the impression block includes a first layer and a second layer, wherein the first layer is of lesser density than the second layer. Alternatively, the impression block is contained within a compliant
Still an additional embodiment includes a method for forming a complete digitized model of the height of a plantar contour of a foot of a user, wherein the plantar contour has a height. The method comprises: placing the foot of the user into an impression block having a thickness and wherein a compliant medium is disposed between the impression block and the foot, wherein the thickness is sufficient to form an impression of at least a portion of the height of the plantar contour; filling the impression with a material which is capable of making a mold of the impression; forming a digitized model of the mold; and extrapolating data from the digitized model of the mold to form either a complete or partial digitized model of the full or partial height of the plantar contour, respectively.